mxs: spl: replace bogus early_delay() function with standard udelay() calls

[karo-tx-uboot.git] / doc / README.falcon

diff --git a/doc/README.falcon b/doc/README.falcon
index 93e855d20eac55a4779c583f7da68c3299c11055..e9f8a7583c721cd96eb364ff23d591c0284c70b3 100644 (file)
--- a/doc/README.falcon
+++ b/doc/README.falcon
@@ -31,9 +31,10 @@ informed to load it before running the kernel.
 To boot the kernel, these steps under a Falcon-aware U-Boot are required:
 
 1. Boot the board into U-Boot.
-Use the "spl export" command to generate the kernel parameters area or the DT.
-U-Boot runs as when it boots the kernel, but stops before passing the control
-to the kernel.
+After loading the desired legacy-format kernel image into memory (and DT as
+well, if used), use the "spl export" command to generate the kernel parameters
+area or the DT.  U-Boot runs as when it boots the kernel, but stops before
+passing the control to the kernel.
 
 2. Save the prepared snapshot into persistent media.
 The address where to save it must be configured into board configuration
@@ -41,6 +42,8 @@ file (CONFIG_CMD_SPL_NAND_OFS for NAND).
 
 3. Boot the board into Falcon Mode. SPL will load the kernel and copy
 the parameters which are saved in the persistent area to the required address.
+If a valid uImage is not found at the defined location, U-Boot will be
+booted instead.
 
 It is required to implement a custom mechanism to select if SPL loads U-Boot
 or another image.
@@ -78,6 +81,19 @@ spl_start_uboot() : required
                Returns "0" if SPL should start the kernel, "1" if U-Boot
                must be started.
 
+Environment variables
+---------------------
+
+A board may chose to look at the environment for decisions about falcon
+mode.  In this case the following variables may be supported:
+
+boot_os :              Set to yes/Yes/true/True/1 to enable booting to OS,
+                       any other value to fall back to U-Boot (including
+                       unset)
+falcon_args_file :     Filename to load as the 'args' portion of falcon mode
+                       rather than the hard-coded value.
+falcon_image_file :    Filename to load as the OS image portion of falcon
+                       mode rather than the hard-coded value.
 
 Using spl command
 -----------------